All-trans retinoic acid-associated low molecular weight water-soluble chitosan nanoparticles based on ion complex

Advances and challenges in retinoid delivery systems in regenerative and therapeutic medicine

Retinoids regulate a wide spectrum of cellular functions from the embryo throughout adulthood, including cell differentiation, metabolic regulation, and inflammation. These traits make retinoids very attractive molecules for medical purposes. In light of some of the physicochemical limitations of retinoids, the development of drug delivery systems offers several advantages for clinical translation of retinoid-based therapies, including improved solubilization, prolonged circulation, reduced toxicity, sustained release, and improved efficacy. In this Review, we discuss advances in preclinical and clinical tests regarding retinoid formulations, specifically the ones based in natural retinoids, evaluated in the context of regenerative medicine, brain, cancer, skin, and immune diseases. Advantages and limitations of retinoid formulations, as well as prospects to push the field forward, will be presented.

Effects of lamellar microstructure of retinoic acid loaded-matrixes on physicochemical properties, migration, and neural differentiation of P19 embryonic carcinoma cells

In this study, retinoic acid loaded-PLGA-gelatin matrixes were prepared with both freeze-casting and freeze-drying techniques. Herein, the effect of unidirectional microstructure with tunable pores on release profile, cellular adhesion, migration, and differentiation was compared. Morphological observation determined that highly interconnected porous structure can be formed, but lamellar pore channels were observed in freeze-casting prepared constructs. The absorption ratio was increased, and the biodegradation rate was decreased as a function of the orientation of microstructure. The in-vitro release study illustrated non-Fickian release mechanism in both methods, so that erosion has predominated over diffusion. Accordingly, PLGA-gelatin scaffolds prepared with freeze-drying technique showed no adequate erosion due to the rigid structure, while freeze-casting one presented more favorable erosion. Microscopic observations of adhered P19 embryonic cells on the scaffolds showed that the freeze-casting matrixes with unidirectional pores provide a more compatible microenvironment for cell attachments and spreading. Besides, it facilitated cell migration and penetration inside the structure and may act as guidance for neuron growth. Improvement in the expression of neural genes in unidirectionally oriented pores proved the decisive role of contact guidance for nerve healing. It seems that the freeze-cast PLGA-gelatin-retinoic acid scaffolds have initial features for nerve tissue regeneration studies.

Synergistic effects of retinoic acid and graphene oxide on the physicochemical and in-vitro properties of electrospun polyurethane scaffolds for bone tissue engineering

Tissue engineering scaffolds simulate extracellular matrixes (ECMs) to promote healing processes of damaged tissues. In this investigation, ECM were simulated by retinoic acid-loaded polyurethane-graphene oxide nanofibers to regenerate bone defects. Scanning electron microscopy (SEM) micrographs, Fourier transform infrared (FTIR) spectrum and X-ray diffraction (XRD) patterns proved the synthesis of graphene oxide (GO) nanosheets. SEM micrographs of nanofibers demonstrated through the formation of homogeneous and bead free fibrous scaffolds that the diameter of fibers were reduced by decreasing the applied voltage in an electrospinning process and the addition of GO. According to the results, the addition of GO to the polyurethane (PU) solution led to an increase in mechanical strength which is the most important parameter in the hard tissue repair. The GO-containing scaffolds showed an increased wettability, swelling, biodegradation and drug release level. Release behavior in nanocomposite scaffolds followed the swelling and biodegradation mechanisms, so osteogenic expression was possible by incorporating retinoic acid (RA) in PU-GO nanofibrous scaffolds. Biological evaluations demonstrated that composite scaffolds are biocompatible and support cellular attachment in which RA-loaded samples represented better cellular spreading. In brief, nanocomposite fibers showed desired that the physicochemical, mechanical and biological properties and synergic effects of GO and RA in osteogenic activity of MG-63 cells produced favorable constructs for hard tissue engineering applications.

Mannosylated chitosan nanoparticles for delivery of antisense oligonucleotides for macrophage targeting

The therapeutic potential of antisense oligonucleotides (ASODN) is primarily dependent upon its safe and efficient delivery to specific cells overcoming degradation and maximizing cellular uptake in vivo. The present study focuses on designing mannosylated low molecular weight (LMW) chitosan nanoconstructs for safe ODNs delivery by macrophage targeting. Mannose groups were coupled with LMW chitosan and characterized spectroscopically. Mannosylated chitosan ODN nanoparticles (MCHODN NPs) were formulated by self-assembled method using various N/P ratio (moles of amine groups of MCH to phosphate moieties of ODNs) and characterized for gel retardation assay, physicochemical characteristics, cytotoxicity and transfection efficiency, and antisense assay. Complete complexation of MCH/ODN was achieved at charge ratio of 1:1 and above. On increasing the N/P ratio of MCH/ODN, particle size of the NPs decreased whereas zeta potential (ZV) increased. MCHODN NPs displayed much higher transfection efficiency into Raw 264.7 cells (bears mannose receptors) than Hela cells and no significant toxicity was observed at all MCH concentrations. Antisense assay revealed that reduction in lipopolysaccharide (LPS) induced serum TNF-α is due to antisense activity of TJU-2755 ODN (sequence complementary to 3′-UTR of TNF-α). These results suggest that MCHODN NPs are acceptable choice to improve transfection efficiency in vitro and in vivo.

Uptake of etoposide in CT-26 cells of colorectal cancer using folate targeted dextran stearate polymeric micelles

Targeted drug delivery using folate receptors is one of the most interesting chemotherapeutic research areas over the past few years. A novel folate targeted copolymer was synthesized using dextran stearate coupled to folic acid. FT-IR and NMR spectroscopy were used to confirm successful conjugation. Micelles prepared using this copolymer were characterized for their particle size, zeta potential, critical micelle concentration (CMC), drug loading capacity, and release efficiency. Cytotoxicity and cellular uptake of the micelles were estimated using CT-26 colorectal carcinoma cell line. FT-IR and NMR spectroscopy confirmed production of folate grafted dextran stearate copolymer. Low CMC value indicates that the copolymers are suitable for preparation of stable micelles useful in parenteral dosage forms. Particle size and zeta potential of the targeted nanoparticles were 105.5 ± 2.0 nm and −21.2 mV, respectively. IC₅₀ of etoposide loaded in folate grafted dextran stearate enhanced about 20-fold compared to the pure drug (0.49 ± 0.11 μg/mL versus 9.41 ± 0.52 μg/mL). It seems that etoposide loaded in micelles of folate grafted dextran stearate copolymer is promising in reducing drug resistance of colorectal cancer by boosting etoposide cellular uptake.

Promising interaction between nanoencapsulated lutein with low molecular weight chitosan: characterization and bioavailability of lutein in vitro and in vivo

This study aims to develop water-soluble low molecular weight chitosan (LMWC) nanoencapsules with lutein to improve its bioavailability. Lutein-LMWC nanoencapsules were prepared, characterized and bioavailability was studied in vitro and in vivo with lutein in mixed micelles (control). The particle size ranged between 80-600 nm, which was confirmed by Atomic Force Microscope. The interaction between LMWC and lutein in nanocencapsules by (1)H and (13)C NMR showed the essentiality of water molecules to hold the lutein between LMWC chains of nanoparticle with a reversible weak bond. Bioavailability of lutein (200 μM) in vitro showed that lutein-LMWC nanoencapsules was significantly higher (27.7%) than control. Postprandial lutein level in the plasma (54.5%), liver (53.9%) and eyes (62.8%) of mice fed on nanoencapsulated lutein were higher than the control. LMWC may serve as novel carrier for enhancing the lutein bioavailability and can be suggested as the better dietary compound in food and pharmaceutical applications.

Controlling the neuronal differentiation of stem cells by the intracellular delivery of retinoic acid-loaded nanoparticles

The manipulation of endogenous stem cell populations from the subventricular zone (SVZ), a neurogenic niche, creates an opportunity to induce neurogenesis and influence brain regenerative capacities in the adult brain. Herein, we demonstrate the ability of polyelectrolyte nanoparticles to induce neurogenesis exclusively after being internalized by SVZ stem cells. The nanoparticles are not cytotoxic for concentrations equal or below 10 μg/mL. The internalization process is rapid, and nanoparticles escape endosomal fate in a few hours. Retinoic acid-loaded nanoparticles increase the number of neuronal nuclear protein (NeuN)-positive neurons and functional neurons responding to depolarization with KCl and expressing NMDA receptor subunit type 1 (NR1). These nanoparticles offer an opportunity for in vivo delivery of proneurogenic factors and neurodegenerative disease treatment.

Influence of histidine on the release of all-trans retinoic acid from self-assembled glycol chitosan nanoparticles

OBJECTIVE

In this study, the influence of N-acetyl histidine (NAHis) on the all-trans retinoic acid (ATRA) release from the NAHis-conjugated self-assembled glycol chitosan (GC) nanoparticles was investigated.

METHODS

NAHis was conjugated to GC as a hydrophobic moiety to prepare the self-assembled nanoparticles, and ATRA was incorporated into the inner core of the NAHis-GC nanoparticles. The ATRA release from NAHis-GC nanoparticles was performed at 37 degrees C in a phosphate-buffered saline buffer (pH 5.5 or 7.4) for 48 hours.

RESULTS

At a pH of 5.5, less than 20% (w/w) of total loading amount of ATRA was released from the nanoparticles after 48 hours. In contrast, two times greater amount of ATRA was released at a pH of 7.4. The ATRA release rate from the NAHis-GC nanoparticles was significantly slower at a pH of 5.5 than at a pH of 7.4.

CONCLUSION

The release profiles of ATRA that was incorporated into the NAHis-GC nanoparticles were controlled by the NAHis content in the GC nanoparticles.

Methotrexate-incorporated polymeric nanoparticles of methoxy poly(ethylene glycol)-grafted chitosan

We prepared methotrexate (MTX)-encapsulated polymeric nanoparticles using methoxy poly(ethylene glycol) (MPEG)-grafted chitosan (ChitoPEG) copolymer. MTX-encapsulated polymeric nanoparticles of ChitoPEG copolymer has around 50-300nm in particle size and showed spherical shape when observed by transmission electron microscope (TEM). In (1)H nuclear magnetic resonance (NMR) study, the specific peaks of MTX and chitosan as a drug carrying inner-core disappeared at D(2)O and only the specific peak of MPEG was observed, while specific peaks of MPEG, MTX, and chitosan appeared in DCl/D(2)O mixtures. These results indicated that MTX was complexed with chitosan and then core-shell type nanoparticles had formed in aqueous environment, i.e., MTX/chitosan complexes composed of inner-core and MPEG composed of outer-shell of the nanoparticles. Loading efficiency of MTX in the polymeric nanoparticles was 94% (w/w) of ChitoPEG-1, 91.1% (w/w) of ChitoPEG-2, 90.1% (w/w) of ChitoPEG-3 and 65.2% (w/w) of ChitoPEG-4, expectively. The higher the drug feeding ratio, the higher the drug content and the lower the loading efficiency. The higher the MPEG graft ratio in the copolymer, the lower the drug content and loading efficiency. Drug contents evaluated by (1)H NMR were the same as found by UV spectrophotometer.

Cyclodextrin conjugated magnetic colloidal nanoparticles as a nanocarrier for targeted anticancer drug delivery

A novel magnetic nanocarrier (CD-GAMNPs) was fabricated for targeted anticancer drug delivery by grafting cyclodextrin (CD) onto gum arabic modified magnetic nanoparticles (GAMNPs) using hexamethylene diisocyanate (HMDI) as a linker. Analyses by transmission electron microscopy (TEM) and dynamic light scattering (DLS) revealed that the product had a mean diameter of 17.1 nm and a mean hydrodynamic diameter of 44.1 nm. The CD grafting was confirmed by Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA) indicated that the amount of CD grafted on the GAMNPs was 16.8 mg g(-1). The study on the loading of anticancer drug all-trans-retinoic acid (retinoic acid) revealed that the newly fabricated magnetic nanocarrier possessed a considerably higher adsorption capability as compared to GAMNPs due to the special hydrophobic cavity structure of CD, which could act as a host-guest complex with retinoic acid. Furthermore, it was found that the complexation of CD-GAMNPs with retinoic acid was exothermic and the presence of a surfactant (sodium dodecyl sulfate) led to the decrease in the inclusion of retinoic acid because the linear structure of sodium dodecyl sulfate made it easier to enter the cavity of CD as compared to less linear retinoic acid. In addition, the in vitro release profile of retinoic acid from CD-GAMNPs was characterized by an initial fast release followed by a delayed release phase.

Preparation and spectroscopic characterization of methoxy poly(ethylene glycol)-grafted water-soluble chitosan

The object of this study was to test the solubility of a methoxy poly(ethylene glycol) (MPEG)-grafted chitosan copolymer in organic solvents and aqueous solution. Water-soluble chitosan with low molecular weight (LMWSC) was used in a PEG-graft copolymerization. The MPEG was conjugated to chitosan using 4-dicyclohexylcarbodimide (DCC), and N-hydroxysuccimide (NHS). Introduction of PEG was confirmed by (1)H and (13)C NMR spectroscopy and FT-IR spectroscopy. The degree of substitution (DS) of MPEG into chitosan was calculated from (1)H NMR data and also by estimating the molecular weight (MW) using gel permeation chromatography (GPC). The DS values obtained from (1)H NMR spectroscopy and GPC were similar, indicating that MPEG-grafted LMWSC was synthesized and properly characterized. Furthermore, the introduction of PEG into chitosan increases the solubility in aqueous solutions over a range of pH values (4.0-11.0) and organic solvents such as DMF, DMSO, ethanol, and acetone.